1. Field of the Invention
The handling of toxic materials, and more particularly the packaging of low level radioactive wastes for storage until radioactivity decays.
2. Brief Description of the Prior Art
Nuclear power plants and various other facilities that handle nuclear material, such as plants for manufacturing nuclear fuels and tracers, use substantial quantities of water in the operational process for cooling machinery and for washing radioactively contaminated parts. This water picks up various minerals, salts, and other materials that become contaminated with radioactive isotopes. Water treatment apparatus is therefore used to periodically remove these contaminants from the water. The removed material is generally discharged either as a low radiation level particulate sludge or aqueous solution that is mixed with a non-radioactive encapsulation, solidification or other immobilization material and then stored in a barrel or other suitable containment container until radioactivity decays.
The immobilization material is used to prevent dispersion of the particulate radioactive material if the barrel is ruptured. Generally, either cement, ureaformaldehyde, or a petroleum organic material such as asphalt, bitumin, polyethylene or paraffin is used for immobilization. The radioactive waste particles mix evenly with the immobilization material and become uniformly dispersed both within and at the surface of the immobilizing material. Any crack or break in the outer container wall will expose a substantial quantity of radioactive material to water and other leaching agents capable of dispersing radioactive contamination, because the immobilization materials shrink slightly away from the walls of the container as they solidify. And, the entire package can be quickly destroyed because some of the immobilization materials also absorb water which causes them to swell, break apart, and thus permit dispersion of substantially all radioactive material.